#!/usr/bin/env bash
# unlock-display-ram.sh — TEMPORARY 2 GiB display-reserve unlock.
#
# Remods nvidia_drm with modeset=1 fbdev=0 so the headless DGX Spark's
# display framebuffer reserve (2 GB in firmware; 1.75 GiB usable as an
# external CUDA memory pool) becomes available to the EXL3 2x runtime
# (libds41_display_kv.so maps /dev/dri/card0 into the KV allocator).
#
# Temporary by design: no UEFI/firmware change, no /etc/modprobe.d entry,
# no initramfs change — the state resets to firmware defaults on reboot.
# Counterpart: restore-display-ram.sh (plain modprobe back).
#
# Requires the GPU to be idle (nvidia_drm in use by a running container
# will refuse rmmod).
set -euo pipefail

if [ -d /sys/module/nvidia_drm ]; then
    modeset=$(cat /sys/module/nvidia_drm/parameters/modeset)
    fbdev=$(cat /sys/module/nvidia_drm/parameters/fbdev)
    if [ "$modeset" = "Y" ] && [ "$fbdev" = "N" ]; then
        if [ -e /dev/dri/card0 ]; then
            echo "nvidia_drm already modeset=1 fbdev=0, /dev/dri/card0 present"
            exit 0
        fi
        echo "nvidia_drm modeset=1 fbdev=0 but /dev/dri/card0 missing — remod anyway"
        sudo rmmod nvidia_drm
    else
        echo "current nvidia_drm: modeset=$modeset fbdev=$fbdev — remodding"
        sudo rmmod nvidia_drm
    fi
fi

sudo modprobe nvidia_drm modeset=1 fbdev=0

[ "$(cat /sys/module/nvidia_drm/parameters/modeset)" = "Y" ] || {
    echo "ERROR: modeset not active after modprobe" >&2; exit 1; }
[ "$(cat /sys/module/nvidia_drm/parameters/fbdev)" = "N" ] || {
    echo "ERROR: fbdev not disabled after modprobe" >&2; exit 1; }
if [ ! -e /dev/dri/card0 ]; then
    sleep 2
fi
[ -e /dev/dri/card0 ] || { echo "ERROR: /dev/dri/card0 missing after modprobe" >&2; exit 1; }
echo "display reserve unlocked: nvidia_drm modeset=1 fbdev=0, /dev/dri/card0 present"